OP497
Rev. E | Page 10 of 16
APPLICATIONS INFORMATION
Extremely low bias current makes the OP497 attractive for use
in sample-and-hold amplifiers, peak detectors, and log amplifiers
that must operate over a wide temperature range. Balancing
input resistances is not necessary with the OP497. High source
resistance, even when unbalanced, only minimally degrades the
offset voltage and TCV
OS
.
The input pins of the OP497 are protected against large differential
voltage by back-to-back diodes and current-limiting resistors.
Common-mode voltages at the inputs are not restricted and
may vary over the full range of the supply voltages used.
The OP497 requires very little operating headroom about the
supply rails and is specified for operation with supplies as low as
±2 V. Typically, the common-mode range extends to within 1 V
of either rail. When using a 10 kΩ load, the output typically
swings to within 1 V of the rails.
AC PERFORMANCE
The ac characteristics of the OP497 are highly stable over its full
operating temperature range. Figure 30 shows the unity-gain
small signal response. Extremely tolerant of capacitive loading
on the output, the OP497 displays excellent response even with
1000 pF loads (see Figure 31).
10
90
100
0%
20mV 5µs
00309-032
Figure 30. Small Signal Transient Response (C
LOAD
= 100 pF, A
VCL
= +1)
10
90
100
0%
20mV 5µs
0309-033
Figure 31. Small Signal Transient Response (C
LOAD
= 1000 pF, A
VCL
= +1)
10
90
100
0%
2V 50µs
00309-034
Figure 32. Large Signal Transient Response (A
VCL
= +1)
–IN
+IN
2.5kΩ
+
V
OUT
V–
2.5kΩ
00309-031
Figure 33. Simplified Schematic Showing One Amplifier
